With gradual development of the society, cars are becoming increasingly popular. Traveling by cars provides people with a convenient manner of transportation, but also causes negative impact on the human society, for example, traffic jams in urban areas and frequent traffic accidents. Obviously, an intelligent transportation system (ITS) needs to be established for the development of the society.
Currently, Vehicles may obtain road condition information or receive other service information by means of vehicle to vehicle (V2V) communication or vehicle to infrastructure (V2I) communication, and a network used in V2V and V2I communication is referred to as a vehicular network. Specifically, a vehicle may broadcast, to a nearby vehicle by means of V2V communication, driving information such as a speed of the vehicle, a driving direction, a specific location, or whether emergent braking is performed. Therefore, a driver of a vehicle that obtains driving information of a nearby vehicle may better perceive a traffic condition beyond the line of sight, so as to predict in advance and avoid a dangerous condition. For the V2I communication, in addition to the foregoing exchange of driving information, the infrastructure of transportation may further provide various types of service information and support of a data network to vehicles, thereby improving the intelligence of transportation.
A Long Term Evolution (LTE) technology is currently a mainstream wireless communications technology, and has desirable network coverage. Therefore, V2V communication and V2I communication are combined with the LTE technology to improve communication performance of a vehicular network. Because a manner of allocating transmission resources in the LTE technology is a centralized control manner, a base station schedules and configures transmission resources in a centralized manner for terminals, that is, vehicles or the infrastructure of transportation, so that a resource collision problem is avoided, thereby ensuring QoS of a service. The resource collision problem occurs as multiple terminals contend for one same transmission resource when a free contention manner is used to obtain a transmission resource. However, in a vehicular network, in both the communication V2V and V2I communication, a vehicle needs to frequently send information such as driving information to a nearby vehicle or the infrastructure of transportation and frequently receive information such as driving information sent by another vehicle or the infrastructure of transportation. Each time when data is sent, a sending request needs to be reported to the base station, and the base station allocates a transmission resource and notifies, by using signaling, a terminal of the allocated transmission resource. Therefore, frequent data transmission of a vehicle results in frequent signaling interactions with the base station. Consequently, signaling overheads of the base station are increased. In addition, the base station also needs to allocate transmission resources multiple times. As a result, load of the base station is increased, and work efficiency of the base station is reduced.